As a developer, I need to be able to see my files in /data/data/(classname), but I don't want to root my tablet. Found out one can read files in /data/data/(classname) by using run-as (classname) after getting into the shell (i.e., adb shell), but this is giving me "package x.x.x is unknown".

Seeing, upon searching, that this is a Samsung issue, perhaps with this particular Android release. Went to Samsung support chat, but the 'technical support' could not help.